Fortescue's Forrest Exits as CEO at Pivotal Time

PERTH, Australia—Australian billionaire Andrew Forrest is stepping down as chief executive of Fortescue Metals Group Ltd. on Monday, just as the mining company embarks on a risky new strategy.

Fortescue is investing more than $8 billion over two years to triple its output of iron ore from Western Australia's remote Pilbara region, which already supplies 40% of the world's trade in the metal. The move comes as commodities demand slows...